Thermoelectric deposit monitor

Abstract

Fluid flow systems can include one or more thermoelectric devices in contact with the fluid flowing through the system. One or more thermoelectric devices can be operated in a temperature control mode and a measurement mode. Thermal behavior of the one or more thermoelectric devices can be analyzed to characterize a level of deposit formed on the thermoelectric device(s) from the fluid flowing through the system. Characterizations of deposition on thermoelectric devices operated at different temperatures can be used to establish a temperature-dependent deposition profile. The deposition profile can be used to determine if depositions are likely to form at various locations in the system, such as at a use device or in a flow vessel. Detected deposit conditions can initiate one or more corrective actions that can be taken to remove deposits, or to prevent or minimize deposit formation before deposits negatively impact operation of the system.

The invention claimed is: 
     
       1. A method for characterizing a level of deposits from a process fluid in a fluid flow system comprising:
 operating a thermoelectric device in a temperature control mode of operation in order to adjust the temperature of the thermoelectric device and induce a deposit from the process fluid to form on a surface of the thermoelectric device in fluid communication with the process fluid, the temperature control mode of operation comprising applying electrical power to the thermoelectric device in order to adjust the temperature thereof, wherein operating the thermoelectric device in the temperature control mode of operation in order to adjust the temperature of the thermoelectric device comprises applying a fixed amount of electrical power to the thermoelectric device in a first polarity in order to reduce the temperature of the thermoelectric device and induce cold deposits on the surface of the thermoelectric device; 
 periodically determining the temperature of the thermoelectric device; 
 observing changes in thermal behavior of the thermoelectric device, comprising
 observing the change in temperature of the thermoelectric device over time while operating the thermoelectric device at the fixed operating power; 
 
 characterizing the level of deposits from the process fluid onto the thermoelectric device based only on the observed changes in thermal behavior of the thermoelectric device, comprising associating a rate of change in the temperature of the thermoelectric device at the fixed operating power with a level of deposit from the process fluid; and 
 applying electrical power to the thermoelectric device in a second polarity; the second polarity being opposite the first, in order to increase the temperature of the thermoelectric device to remove the cold deposits from the surface of the thermoelectric device. 
 
     
     
       2. The method of  claim 1 , wherein periodically determining the temperature of the thermoelectric device comprises measuring the temperature of the thermoelectric device via one or more measurement device. 
     
     
       3. The method of  claim 1 , wherein:
 operating the thermoelectric device in a temperature control mode of operation comprises applying electrical power to the thermoelectric device to operate the thermoelectric device at a fixed temperature; 
 periodically determining the temperature of the thermoelectric device provides feedback to confirm the thermoelectric device is operating at the fixed temperature; 
 observing changes in the behavior of the thermoelectric device comprises observing a change in the electrical power required to operate the thermoelectric device at the fixed temperature; and 
 characterizing the level of deposit from the process fluid comprises associating the rate of change of applied power required to operate the thermoelectric device at the fixed temperature with a level of deposit from the process fluid. 
 
     
     
       4. The method of  claim 1 , wherein:
 observing changes in the behavior of the thermoelectric device comprises measuring the rate at which the temperature of the thermoelectric device changes due to the operating the thermoelectric device in the temperature control mode; and 
 characterizing the level of deposit from the process fluid onto the thermoelectric device comprises associating the rate the temperature of the thermoelectric device changes with a level of deposit from the process fluid. 
 
     
     
       5. The method of  claim 1 , wherein the thermoelectric device comprises a Peltier device. 
     
     
       6. The method of  claim 1 , wherein periodically determining the temperature of the thermoelectric device comprises periodically switching between the temperature control mode of operation and a measurement mode of operation in order to determine the temperature of the thermoelectric device. 
     
     
       7. The method of  claim 6 , wherein determining the temperature of the thermoelectric device comprises measuring a voltage across the thermoelectric device to determine the temperature of the thermoelectric device. 
     
     
       8. A method for characterizing an amount of deposits from a process fluid in a fluid flow system comprising:
 operating a thermoelectric device in a temperature control mode of operation in order to adjust the temperature of the thermoelectric device and induce a deposit from the process fluid to form on a surface of the thermoelectric device in fluid communication with the process fluid, the temperature control mode of operation comprising applying electrical power to the thermoelectric device in order to adjust the temperature thereof; 
 periodically determining the temperature of the thermoelectric device; 
 observing changes in thermal behavior of the thermoelectric device; and 
 determining the amount of deposits from the process fluid present on the thermoelectric device based only on the observed changes in thermal behavior of the thermoelectric device. 
 
     
     
       9. The method of  claim 8 , further comprising applying electrical power to the thermoelectric device in a second polarity, the second polarity being opposite the first, in order to increase the temperature of the thermoelectric device to remove the cold deposits from the surface of the thermoelectric device. 
     
     
       10. The method of  claim 8 , wherein operating the thermoelectric device in the temperature control mode of operation in order to adjust the temperature of the thermoelectric device comprises applying a fixed amount of electrical power to the thermoelectric device in a first polarity in order to reduce the temperature of the thermoelectric device and induce cold deposits on the surface of the thermoelectric device. 
     
     
       11. The method of  claim 10 , wherein determining the amount of deposits from the process fluid onto the thermoelectric device based on the observed changes in thermal behavior of the thermoelectric device comprises associating the rate of change in the temperature of the thermoelectric device at the fixed operating power with the amount of deposit from the process fluid.